How to initialize a DT028ATFT display

Question

I am trying to initialize a DT028ATFT-TS display on an STM32F10B main board. The system worked with DT028TFT-TS before, but that display has been discontinued. As a result of using the new diplay, the interface also had to change from ILI9320 to ILI9341. I am now basically trying to initialize the new display in a configuration that would be equivalent to what I had before.

The problem I am facing is that the display image ends up showing horizontal streaks randomly distributed (slightly different at every startup) with a bit of a flicker. And, at times (not sure if related), it just shows the backlight and nothing else - no streaks, no test image. The test image is just one big red square (100x100) displayed at x=100, y=50. You can see the effect of the problem here: Streaked Display Image.

The following is part of the initialization code that I've used - part of it taken as such from DisplayTech's sample code offered on their website, part of it customized. I've excluded commands from the sample code that are not documented under ILI9341 (probably vendor customization) and the gamma correction parameters, just to save some space. Any help in finding out where I went wrong would be appreciated.

// DT028ATFT LCD init - ILI9341:
// Frame Rate Control
SPI_WriteCMD(0xB1);
SPI_WriteDAT(0x00);     // division ratio: 1
SPI_WriteDAT(0x10);     // 16 clocks per line
// Power Control
SPI_WriteCMD(0xC0);
SPI_WriteDAT(0x25);     // GVDD = 4.70V
SPI_WriteCMD(0xC1);
SPI_WriteDAT(0x03);     // VCL=VCI x 2, VGH=VCI x 6, VGL=-VCI x 3
// VCOM Control
SPI_WriteCMD(0xC5);
SPI_WriteDAT(0x5C);     // VCOMH = 5.000 V
SPI_WriteDAT(0x4C);     // VCOML = -0.600 V
SPI_WriteCMD(0xC7);
SPI_WriteDAT(0x94);     // VCOMH = VMH - 44, VCOML = VML - 44
// Memory Access Control
SPI_WriteCMD(0x36);
SPI_WriteDAT(0x08);     // BGR=1, Normal addr order and refresh direction
// Write CTRL Display
SPI_WriteCMD(0x53);
SPI_WriteDAT(0x24);     // BCTRL=1, DD=0, BL=1
// Display Function Control
SPI_WriteCMD(0xB6);
SPI_WriteDAT(0x00);     // Normal scan, V63 pos pol / V0 neg pol
SPI_WriteDAT(0xA0);     // LCD normally white, G1 to G320, S720 to S1
SPI_WriteDAT(0x27);     // NL = 320
SPI_WriteDAT(0x00);     // PCDIV not used
// Entry Mode Set
SPI_WriteCMD(0xB7);
SPI_WriteDAT(0x06);     // Normal display for G1-G320 output, Low voltage detection enabled
// Column Address Set
SPI_WriteCMD(0x2A);
SPI_WriteDAT(0x00);
SPI_WriteDAT(0x00);     // Start Column = 0
SPI_WriteDAT(0x00);
SPI_WriteDAT(0xEF);     // End Column = 239
// Page Address Set
SPI_WriteCMD(0x2B);
SPI_WriteDAT(0x00);
SPI_WriteDAT(0x00);     // Start Page = 0
SPI_WriteDAT(0x01);
SPI_WriteDAT(0x3F);     // End Page = 319
// Gamma Set
SPI_WriteCMD(0x26);
SPI_WriteDAT(0x01);     // Gamma Curve 1 selected (G2.2)
// Pixel Format Set
SPI_WriteCMD(0x3A);
SPI_WriteDAT(0x55);     // 16bits/pixel (RGB and MCU i/f)
// Interface Control
SPI_WriteCMD(0xF6);
SPI_WriteDAT(0x00);     // image data not wrapped around (exceeding data ignored)
SPI_WriteDAT(0x00);     // MSB used also as LSB for R and B (64k colours)
SPI_WriteDAT(0x00);     // Disp Op Mode: internal clk, GRAM access: Sys I/F, 1 transf/pxl (16bit 64k colours)
// RGB Interface Signal Control
SPI_WriteCMD(0xB0);
SPI_WriteDAT(0xC0);     // BypassMode=1, RCM=2, VSPL=0, HSPL=0, DPL=0, EPL=0
// Sleep Mode off (DC/DC conv enabled, internal osc started)
SPI_WriteCMD(0x11);
Dly100us((void*)1200);
// Display ON
SPI_WriteCMD(0x29);
// ===============================

Answer 1

your problem sounds like a timing issue. Have you tried reducing the frame rate? that should relax the display timing. you are setting it to 119 Hz.

are you doing a proper reset before the init?

you can compare with other implementations for the ILI9341 controller:

• Example
• Atmel Library